The present invention relates to a sound arresting device for use in a supply/exhaust air duct of a building, an automobile muffler and a rolling stock muffling wall.
In order to deaden noise at its source, it is preferred to surround the source with a sound insulating wall. However, if a power chamber housing an engine or motor is closed, the air flow inside the power chamber will be interrupted. For this reason, it is physically impossible to enclose the noise source in the air duct or the automobile muffler.
For this reason, various types of sound arresting devices have been conventionally proposed to deaden noise while guaranteeing that air will continue to circulate. A sound arresting device of this type is described in Japanese Patent Disclosures No. 55-60790, 55-107853 and 58-28503. Another sound arresting device for deadening noise generated from rolling stock is described in Japanese Patent Disclosure No. 55-113098.
However, the silencing effect of these sound arresting devices is not satisfactory. Their construction is so complex that they are difficult to manufacture.
Additionally, mufflers often contain gas which has a foreign material such as dust (e.g., exhaust gas from a vehicle). The conventional mufflers fail to remove such foreign material from the gas.